Long Term Evolution (LTE) is the name given to a project within the Third Generation Partnership Project (3GPP) to improve the Universal Mobile Telecommunications System (UMTS) mobile phone standard to cope with future requirements. Goals include improving efficiency, lowering costs, improving services, making use of new spectrum opportunities, and better integration with other open standards.
LTE networks rely on Orthogonal Frequency Division Multiplexing (OFDM) as well as on Multiple-Input Multiple-Output (MIMO) antenna technologies. Based on these technologies it should be possible for cellular phone network providers to handle much more users (approximately ten time more users than UMTS) and to support not only speech data but also services such as interactive applications including high speed data transfer and Internet Protocol Television (IPTV).
The architecture of LTE networks is characterized by the fact that no central base station controller manages the handovers of a cellular mobile phone between cells being assigned to different base stations. A base station in a LTE network is called evolution NodeB (eNodeB). With a LTE cellular network the eNodeB potentially in conjugation with the cellular mobile phone decides to handover a call to a cell of another eNodeB. In the following a cellular mobile phone will also be called a User Equipment (UE).
In Wideband Code Division Multiple Access (WCDMA) networks a configuration of a UE for performing measurements such as inter-frequency measurements is defined by a Radio Network Controller (RNC) and provided to the UE. During an inter-frequency measurement the UE tunes its receiver for certain subsequent times towards a different frequency in order to detect signals from other base stations operating at different frequencies. Specifically, in WCDMA the UE measurement configuration can be divided in two configuration parts. A first part is the so called compressed mode configuration and a second part is the so called compressed mode activation. Thus, after a handover of the UE it is not necessary to completely renew the whole UE measurement configuration. Rather it is only necessary that the RNC activates the measurement configuration. Thereby, a new activation time is provided by the RNC both to the UE and to the affected new base station.
As has already mentioned above, in LTE networks there is no central base station controller which can ensure that a UE measurement configuration is provided to all base stations being involved in a handover of the UE. Therefore, in order to ensure that all base stations being involved in a handover have a knowledge of the actual measurement configuration, data representing the actual measurement configuration have to be transmitted between the UE and the new respectively the target base station via the air interface between the UE and the target base station. This has the disadvantage that the data load of the air interface will be increased.
There may be a need for providing an effective method for handing over a User Equipment from a first base station to a second base station of a cellular telecommunication network.